Black smoke ashes form at the end of tail pipe

Maintenance/Repairs
1

I don’t know how to put this in English. There’s a black form around the end of my minivan tail pipe. This form is created by smoke, I can have it on my finger if I touch it (like BBQ ashes), is this normal or my minivan running rich? I don’t see any black smoke coming out of the tail pipe as it is driving, thanks.

2

Make, model, year, miles?

3

Normally when I look at used cars to buy I do check the tailpipe, a gray ash is preferred. It really depends on how much of a buildup you have. For many engines that last many miles it is kind of normal but an indicator to me that the engine is wearing out or needs some maintenance. Keep up with maintenance in the manual and if there are no check engine lights etc. drive on. Some techron or seafome might help, but imhop not a cause for immediate concern.

4

cityboy
There’s a black form around the end of my minivan tail pipe. This form is created by smoke, I can have it on my finger if I touch it (like BBQ ashes)…

Be glad it’s dry and not damp.

…is this normal or my minivan running rich?

How is your fuel economy? Check Engine Light on?

I don’t see any black smoke coming out of the tail pipe as it is driving, thanks.

You said: This [black] form is created by smoke…
Have you actually seen any smoke or not?

5

The black is actually carbon deposition. In every vehicle’s combustion process, there will be some carbon emitted. Gasoline is a hydrocarbon, hydrogen atoms bonded to carbon atoms. The process of combustion tears these apart and bonds the hydrogen atoms to the oxygen in the air forming H2O and the carbon to the oxygen forming CO2 (ideally) and some CO. Some of the carbon never gets bonded and is emitted via the exhaust. Modern catalytic conversion systems try to bond some of that loose carbon to CO molecules, but they aren’t 100% either.

How much depends on the age and wear of the engine, the engine’s design (some are more prone than others for a variety of technical reasons), the engine’s maintenance, and the engine’s mileage. If you don’t keep your car tuned and running properly you’ll end up with carbon.

And remember that oil is a hydrocarbon too. If you burn oil, you produce carbon.

So, with the year, make, mileage, and maintenance history we can venture a guess. Without that, we can only assume the engine is old and worn.